Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/02—Investigating particle size or size distribution
  • G01N15/0205—Investigating particle size or size distribution by optical means
  • G01N15/0227—Investigating particle size or size distribution by optical means using imaging; using holography
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/10—Investigating individual particles
  • G01N15/14—Optical investigation techniques, e.g. flow cytometry
  • G01N15/1456—Optical investigation techniques, e.g. flow cytometry without spatial resolution of the texture or inner structure of the particle, e.g. processing of pulse signals
  • G01N15/1459—Optical investigation techniques, e.g. flow cytometry without spatial resolution of the texture or inner structure of the particle, e.g. processing of pulse signals the analysis being performed on a sample stream
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/26—Oils; Viscous liquids; Paints; Inks
  • G01N33/28—Oils, i.e. hydrocarbon liquids
  • G01N33/2823—Raw oil, drilling fluid or polyphasic mixtures
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/10—Investigating individual particles
  • G01N15/14—Optical investigation techniques, e.g. flow cytometry
  • G01N15/1429—Signal processing
  • G01N15/1433—Signal processing using image recognition
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/10—Investigating individual particles
  • G01N15/14—Optical investigation techniques, e.g. flow cytometry
  • G01N2015/1486—Counting the particles
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
  • G01N15/10—Investigating individual particles
  • G01N15/14—Optical investigation techniques, e.g. flow cytometry
  • G01N2015/1497—Particle shape

Definitions

• the present invention relates to methods for determining the presence and proportion of certain additives in fluids, and more particularly relates, in one embodiment, to methods for determining the presence and proportion of bridging agents in aqueous drilling fluids, drill-in fluids and completion fluids.
• Drilling fluids used in the drilling of subterranean oil and gas wells as well as other drilling fluid applications and drilling procedures are known.
• drilling fluids also known as drilling muds, or simply “muds”.
• the drilling fluid is expected to carry cuttings up from beneath the bit, transport them up the annulus, and allow their separation at the surface while at the same time the rotary bit is cooled and cleaned.
• a drilling mud is also intended to reduce friction between the drill string and the sides of the hole while maintaining the stability of uncased sections of the borehole.
• the drilling fluid is formulated to prevent unwanted influxes of drilling fluid filtrate and drill solids into permeable rocks penetrated and also often to form a thin, low permeability filter cake which temporarily seals pores, other openings and formations penetrated by the bit.
• the drilling fluid may also be used to collect and interpret information available from drill cuttings, cores and electrical logs. It will be appreciated that within the scope of the claimed invention herein, the term “drilling fluid” also encompasses “drill-in fluids” and “completion fluids”.
• Drilling fluids are typically classified according to their base fluid.
• water-based muds solid particles are suspended in water or brine. Oil can be emulsified in the water. Nonetheless, the water is the continuous phase.
• Oil-based muds are the opposite or inverse. Solid particles are suspended in oil, and water or brine is emulsified in the oil and therefore the oil is the continuous phase.
• Oil-based muds that are water-in-oil emulsions are also called invert emulsions.
• Brine-based drilling fluids of course are a water-based mud in which the aqueous component is brine.
• Horizontal wells drilled and completed in unconsolidated sand reservoirs have become feasible due to improvements in technology and completion methods.
• Wells of this type require sand control, for example such as long open hole gravel packs or the installation of mechanical sand exclusion devices (slotted liners, pre-packed and expandable sand screens, etc.).
• Successful wells have been completed with horizontal, producing intervals as long as 5,000 ft. (1224 m) using these methods of sand control.
• a “low damage potential drilling mud” generally consisting of polymers or other thickening agents, viscosity enhancers and insoluble particles for building a filter cake to bridge the pores in the sandstone reservoir.
• the particles are usually graded salt (NaCl) in saturated brine or graded calcium carbonate (CaCO 3 ) in any fluid, and as technology has improved, the particle size distribution as compared with the pore throat openings of the reservoir has become more important.
• Sodium chloride and calcium carbonate are used because they are soluble in undersaturated brines or inorganic and/or organic acids, respectively.
• PSD particle size distribution
• This matching is fairly straightforward in preparing the initial drill-in fluid and can be verified by, for example, laser light scattering prior to drilling since the bridging agent is typically the only particulate solid present. Once drilling begins, however, the drill-in fluid becomes contaminated with drill solids (cuttings) and other particulate components such as weighting agents and laser light scattering will only give the PSD of all the suspended solids—drill solids, weighting agents, and the bridging agent.
• a bridging agent particularly calcium carbonate
• a fluid used for hydrocarbon recovery such as a drilling fluid, drill-in fluid, and/or completion fluid, and the like.
• Still another object of the invention is to provide a method for determining the PSD of a bridging agent, such as calcium carbonate, in a drilling fluid used for hydrocarbon recovery, even in the presence of other particulate solids, such as drill cuttings and weighting agents.
• a bridging agent such as calcium carbonate
• a method for determining a characteristic of a particulate material in a fluid involving exposing a sample of the fluid containing the particulate material to light, observing the fluorescence of the particulate material to produce an image; and calculating a characteristic of the particulate material using the image.
• the particulate material characteristic may be the size of the bridging agent, the amount of the particulate material, or the combination of size and amount of the particulate material expressed as particle size distribution (PSD).
• PSD particle size distribution
• the invention can also be applied to measuring the characteristics (amount, size or both) of an auto-fluorescing particulate in a fluid and especially if that particulate is used as a bridging agent.
• a method for determining a characteristic of an immiscible phase in a fluid that involves exposing a sample of the fluid containing the immiscible phase to light; observing the fluorescence of the immiscible phase to produce an image; and calculating a characteristic of the immiscible phase using the image.
• the characteristic may be the size of the immiscible phase, the amount of the immiscible phase and a combination of size and amount of the immiscible phase.
• the immiscible phase is either an auto-fluorescing immiscible phase or an immiscible phase to which a fluorescent dye has been added.
• bridging agents As well. With respect to bridging agents, it is important to know when to add how much of the proper size of bridging agent, and thus knowing the particle size distribution (PSD) of the bridging agent in the return drilling mud is important.
• PSD particle size distribution
• the method of this invention is expected to be useful in determining the presence, size and/or amount of any immiscible phase in a fluid, where an immiscible phase includes additives and particulate materials (e.g. bridging agents) and any other material in a fluid which is insoluble therein whose presence, size and/or amount can be determined by the instant method.
• an immiscible phase includes additives and particulate materials (e.g. bridging agents) and any other material in a fluid which is insoluble therein whose presence, size and/or amount can be determined by the instant method.
• the method of this invention could be used to determine the size and/or amount of proppant in a fracturing fluid, the size and/or amount of specially sized calcium carbonate in a reservoir drill-in fluid or loss of circulation pill containing sized calcium carbonate.
• portion can refer to the amount of the immiscible phase as well as distribution, which is a combination of size and amount.
• a fluid is described as “aqueous”, it is meant that it contains at least some water, and in a preferred, non-limiting embodiment, contains at least 50 volume % water, and in another preferred, non-limiting embodiment contains water as the continuous phase, whether or not water makes up 50 vol. % of the total fluid.
• the technique of this invention would be useful in determining characteristics of a bridging agent or other auto-fluorescing particulate within a mixture of particulates, such as a powder, as well as in a fluid.
• the method of this invention can be modified or adapted for non-fluorescing particles by incorporation of a suitable dye.
• bridging agents in particular calcium carbonate
• This high level of auto-fluorescence of calcium carbonate can be used to obtain an image of the calcium carbonate distinguishable from the remaining drill solids and weight material that exhibit relatively lower levels of auto-fluorescence.
• image is not limited to any particular medium, and includes, but is not necessarily limited to, images in fixed form such as photographs, images on a screen (cathode ray tube, flat panel display, images perceivable by charge-coupled devices (CCDs), etc. of a temporary nature), images in machine-readable form, etc. Such images may be captured using a microscope having fluorescence imaging capability or other collection objects or electronics.
• the resulting images of just calcium carbonate can then be analyzed using commercial image analysis software programs to calculate the PSD of only the calcium carbonate bridging agents present in field drill-in fluids (or other fluids) contaminated with drill solids.
• the inventive method is particularly useful in analyzing selectively for calcium carbonate. Conventional light-scattering analysis is sensitive to all particles and does not differentiate between bridging agents and drill solids.
• the inventive technique can also be used to trace calcium carbonate particulate invasion of laboratory or field cores after mudding off or coring. If field cores were available on location, the Technical Service Representative (TSR) could test the treated fluid to determine if the bridging agent was performing appropriately on the cores, i.e. if the agent was properly bridging and minimizing invasion as measured by spurt and total filtration losses. Alternatively, simulated cores could be used. The advantage of analyzing this at the drilling location is that appropriate adjustments to the drilling fluids' PSD could be adjusted in a timely manner to avoid potential formation damage caused by fluid and particulate invasion.
• TSR Technical Service Representative
• the pore throat size distribution of the formation is already known (such as from a previously drilled offset well) or can be estimated.
• the TSR could check and adjust the PSD as needed based on the fluorescence data and the known pore size distribution.
• fluoresce and adjustments may need to be made in the inventive process.
• Other components such as an emulsifier or other material may fluoresce at a frequency that might interfere with that of the bridging agent.
• a filter may be used to isolate the fluorescence of interest or reduce the intensity of the interfering fluorescence.
• a filter could be used on the light used to expose the sample, to filter he fluorescing light, or both.
• the light source itself could be of a particular narrow frequency.
• the detector or observation and/or the image produced in the observation of the illuminated immiscible phase could be modified to be sensitive only to a particular, desired wavelength of interest.
• observing the fluorescence of the bridging agent or other immiscible phase means being able to detect the presence, size and/or amount of the immiscible phase from other light that may be present.
• fluorescent dyes could also be used as tracers in the continuous phase of a drilling fluid, as well as to track filtrate invasion in cores, whether field cores or simulated cores.
• a dye could be added to the sample of the fluid (drill-in fluid, e.g.) after the fluid is retrieved from the borehole.
• fluorescent dye is meant any substance that would selectively bind to an immiscible phase or to the continuous phase and preferentially be detectable under observation and/or image production to show the presence of the immiscible phase or the continuous phase, by using either a broad or a narrow wavelength spectrum of light, as necessary or preferable.
• a fluorescent dye is used in both the continuous and the immiscible phases, a different dye would generally be used for each phase, and a different species and/or phase would be examined using each dye. These separately added dyes could be used separately from or in addition to auto-fluorescing particles or agents.
• flow cytometry technology may be used to implement the inventive method.
• Flow cytometry is a method of measuring certain physical and/or chemical characteristics of particles as they travel in a fluid, such as a suspension or a dilute solution of a dispersion, individually past a sensing point, usually an optical detector. The technique can be used to count or measure the characteristics of cells.
• Flow cytometers can be understood to be specialized fluorescence microscopes.
• Flow cytometers include a light source, collection optics, electronics and a computer to translate signals into usable data. Many commercial cytometers use a laser as the light source that emits coherent light at a specified wavelength although broadband light sources can also be used.
• Scattered and emitted fluorescent light is typically collected by two lenses (one set in front of the light source and one set at right angles thereto) and by a series of optics, beam splitters and filters, specific bands of fluorescence can be measured. Physical characteristics such as particle size and shape can be determined, and any function that can be detected by a fluorescent compound can be examined. Many flow cytometers also have the ability to sort or physically separate particles of interest from a sample. An important feature of flow cytometric analysis is that large numbers of particles, for instance on the order of 100,000 or more may be analyzed one after the other in a relatively short period of time (e.g. one minute). In contrast, microscopic analysis is usually based on a limited number of particles (e.g. 1 to 100) seen on a slide.
• the analysis process of the invention would involve first taking a smear of the whole mud or diluted whole mud on a microscope slide. A field or area of the slide would be photographed using fluorescent illumination. Additionally images may also be taken using bright-field transmitted light, reflected light and/or dark-field illumination all with or without polarization. These images would then be analyzed using an image analysis software program to identify the particle boundaries, determine their diameters, and count the particles.
• image analysis software program Commercial programs available to do this type of analysis include, but are not limited to IMAGEPRO and OPTIMUS software marketed by Media Cybernetics, but mention of these programs should not be understood as an endorsement of any kind. Several fields should be used to get a good statistical average of the range of particle diameters.
• this process would be repeated at a range of magnifications to ensure that the full range of sizes was captured.
• a histogram of the particle counts versus particle size range would then give the relative PSD for each type of illumination. If the volume of the sample counted was actually determined, then an absolute PSD could be obtained. Comparison of results using different illumination would be used to discriminate particle types.
• flow cytometry could be employed to count particles in a given volume of a flowing stream as they pass a sensing point.
• the inventive analysis could be done at the rig site in a mobile laboratory, or even in the mud logger's cabin provided it was equipped with a fluorescent microscope with the imaging capability and analysis software.
• the image(s) obtained at the rig site could be electronically transmitted, such as by e-mail or possibly fax, to another location for analysis. It is anticipated that this is the only equipment needed to practice the method of the invention in its basic form, in one non-limiting embodiment.
• the invention has been described with reference to specific embodiments thereof, and has been proposed as effective in providing a reproducible method for determining the size, amount, and/or PSD of bridging agents in fluid systems, such as drilling fluids, drill-in fluids, and completion fluids. Additionally, the method of this invention is expected to be useful in determining the presence, amount, size, and PSD of any auto-fluorescing particulate in other fluids as well, with the expected modifications. Further, it will be evident that various modifications and changes can be made to the inventive method without departing from the broader spirit or scope of the invention as set forth in the appended claims. Accordingly, the specification is to be regarded in an illustrative rather than a restrictive sense.

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• Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
• Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)

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Citations (37)

• 2002
  • 2002-10-30 US US10/283,972 patent/US7050166B2/en not_active Expired - Fee Related
  • 2002-10-31 EA EA200400539A patent/EA006285B1/ru not_active IP Right Cessation
  • 2002-10-31 BR BR0213855-7A patent/BR0213855A/pt not_active IP Right Cessation
  • 2002-10-31 CA CA002466102A patent/CA2466102A1/en not_active Abandoned
  • 2002-10-31 AU AU2002350098A patent/AU2002350098C1/en not_active Ceased
  • 2002-10-31 GB GB0410256A patent/GB2397881B/en not_active Expired - Fee Related
  • 2002-10-31 WO PCT/US2002/034998 patent/WO2003040701A1/en not_active Application Discontinuation
• 2004
  • 2004-06-01 NO NO20042265A patent/NO20042265L/no not_active Application Discontinuation

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